This invention relates to apparatus for partial balancing of the free inertia forces and inertia moments of reciprocating piston-crankshaft engines, particularly inertia forces of the second order in four-cylinder, four-stroke in-line engines and for partial balancing of the free inertia moments of three- and five-cylinder, four-stroke in-line engines.
The existence of inertial forces in reciprocating piston engines is well known. These forces arise from the reciprocating motion of engine components, such as pistons and connecting rods. Most reciprocating piston engines make use of rotating counterweights arranged on the crankshaft for balancing the first order inertial forces occurring in the longitudinal direction of the cylinder. Second order forces can be balanced by use of an arrangement known as the Lanchester equalizer, which makes use of a pair of auxiliary shafts provided with counterweights and connected to the crankshaft by a transmission which causes the auxiliary shafts to rotate at double the crankshaft speed in opposite directions. The Lanchester equalizer arrangement necessitates a comparatively extensive structural arrangement, and therefore significantly increases the cost of the engine. Furthermore, considerable noise arises due to the high revolution speed of the auxiliary shafts and their drives. Another disadvantage of the arrangement is that the auxiliary shaft must be designed into the engine prior to engine design and construction, and subsequent installation of the auxiliary shafts on a reciprocating engine cannot be practically implemented.
In addition to the inertial forces occurring in the longitudinal cylinder direction, which arise from piston throw, there are transverse forces which act on the engine in a direction transverse to the cylinder axes and arise out of the pivoting motion of the connecting rods. These "slideway" forces are the transverse components of the inertial and gas forces acting on the connecting rods due to the swiveling motion of the connecting rods during crankshaft rotation. The transverse forces are second order forces, since they act with cyclical regularity at twice the revolution frequency of the crankshaft.
It is therefore an object of the present invention to provide an apparatus for partial balancing of inertial forces in a reciprocating piston-crankshaft engine.
It is a further object of the invention to provide such an arrangement which may be inexpensively implemented, and which can be adapted to an existing reciprocating engine.
It is a still further object of the invention to provide such an apparatus which compensates for transverse forces as well as longitudinal first and second order inertial forces.